Assertion:  A planar circular loop of area A and carryi

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 Multiple Choice QuestionsMultiple Choice Questions

231.

A long straight wire carries 10 A d.c. current an electron travels perpendicular to the plane of this wire at a distance 0.1 m with velocity  5.0 x 106 ms-1. Force acting on the electron due to current in wire is

  • zero N

  • 0·6 × 10-17 N

  • 2.4 × 10-17 N

  • 2.2 × 10-17 N


232.

Assertion:  A charged particle free to move in an electric field always moves along an electric field line. 

Reason: The electric field lines diverge from a negative charge and converge at a positive charge.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


233.

Assertion:  If an electron and proton possessing same kinetic energy enter an electric field in a perpendicular direction, the path of the electron is more curved than that of the proton. 

Reason:  Electron forms a larger curve due to its small mass.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


234.

Assertion:  Magnetic field is useful in producing parallel beam of charged particle. 

Reason:  Magnetic field inhibits the motion of charged particle moving across it.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


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235.

A wire of mass 100 g, length 1 m and current 5 A is balanced in mid air by a magnetic field B, then find the value of B

  • 0.2 T

  • 0.1 T

  • 0.5 T

  • 0.6 T


236.

A toroid with mean radius r0, diameter 2a have turns carrying current I. What is the magnetic field B outside the toroid?

  • N I2πr0

  • NI2π r0 + a

  • NIπr0 + a

  • zero


237.

Identify incorrect for electric charge q

  • quantised

  • conserved

  • additive

  • non-transferable


238.

Two wires carrying

  • Parallel current repel each other.

  • Antiparallel current attract each other.

  • Antiparallel current repel each other.

  • Equal magnitudes of antiparallel current attract each other.


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239.

Electric field outside a long wire carrying charge q is proportional to

  • 1r

  • 1r2

  • 1r35

  • 1r32


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240.

Assertion:  A planar circular loop of area A and carrying current I is equivalent to magnetic dipole of dipole moment M = IA.

Reason: At large distances, magnetic field of circular loop and magnetic dipole is same.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion.

Magnetic field due to a circular loop carrying current I is given as

            B = μ04π2 πIr2r2 + x232

where, r = radius of loop 

         x = distance from centre of loop 

For large distances, (x > > r),

         B = μ04π2 I Ax3

where M = IA = magnetic dipole moment of current loop which is equal to the magnetic field due to magnetic dipole. 

Thus, the current loop can be considered as a magnetic dipole.


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